The present invention relates to a toothed gearing group for coupling two concentric shafts to a solitary driving shaft.
As known, power is transmitted from a machine to a fluid or from a fluid to a user device with greater efficiency if one uses a pair of counter-rotating propellers. Up to now, energy has been transmitted from a motor to a fluid (air) by using two motors, each designed to drive a respective propeller independently, or by using a single motor but with a drive using planet and crown gear transmission which is similar in principle to the differential of a motor vehicle.
The use of a transmission, however, has the drawback that the solitary input driving shaft is always arranged either at right angles or parallel to the output of the two user shafts; this, in addition to the known drawbacks due to overall dimensions, to weight and the mechanical complexity owing to the use of bevel gears, considerably limits the number of convenient applications.
Moreover, it is impossible to select rotation of the driving shaft concordant with anyone of the twin shafts.